The only thing i will say here is that Garcia is the only "organizer" we have for the backline on this team.
I agree that Gomez is the better defender, but when we played without him (Garcia) back there everybody gets out of sorts. Now maybe in time Attakora, Gomez, etc.. can pull it together, but for now they are guys who are individually talented but need a leader back there with them to keep them in line. I'd also say that Gomez is still working though some very rookie like brain cramps out there. I'd say playing him in moderation is the best call. Let him develop without giving him too much rope to hang himself with.
I think the bottom line is you take two defensively challenged full-backs, one aging slow CB, and one very good young player: the end result is the CB's have to cover for the fullbacks inabilities often, leaving them exposed.
So 3/4 new players on the backline are probably needed, but in the short run, tell Brennan / Wynn to keep it in check or they'll be riding the bench. We need defensive resposibility way more than extra attacking muscle right now.